Charge preheater

ABSTRACT

In a charging material preheater for a metallurgical smelting plant having a shaft (5) which has closure members (7, 8) which are pivotable by a control member (6) and which include fingers (9, 10) which are arranged parallel and at a spacing relative to each other, the fingers (9, 10) of a closure member (7, 8) are mounted with a central portion in a first rotary mounting (12, 13) and in a second rotary mounting (21, 22) of the frame structure (2) with an outer portion which is passed outwardly through an opening (14, 15) in the shaft wall, by way of an elbow lever mechanism (16, 17), and lever arms (18, 19) of at least two elbow lever mechanisms are connected together by a connecting member (23) which is pivotably engaged by a control member (6) which is supported in a third rotary mounting (26, 27) of the frame structure (2).

FIELD OF THE INVENTION

The invention concerns a charging material preheater for preheatingcharging material for a metallurgical smelting plant.

DESCRIPTION OF THE PRIOR ART

A charging material preheater similar to that disclosed herein is knownfrom DE-A1-39 40 558. In the lower region of a shaft-like container theknown charging material preheater has mutually oppositely disposedclosure members which are pivotable by a control member and which eachinclude fingers or grid bars which are arranged in parallel spacedrelationship to each other, the fingers or grid bars being mounted in amounting which is supported on a frame structure of the container andbeing pivotable downwardly from a closed position in which innerportions of the fingers project into the interior of the container intoa release position in which said portions of the fingers face downwardlyand permit material to pass through the container.

With that charging material preheater, when the closure members are inthe closed position, it is possible for charging material to be retainedin the container and heated by hot gases which are passed therethrough,while after the heating operation, the charging material can be emptiedinto a metallurgical vessel disposed therebeneath by pivotal movement ofthe closure members into the release position.

In the known charging material preheater the shaft-like container is ofa rectangular cross-section.

EP-B1-0 291 701 discloses a charging material preheater having ashaft-like container which is fixed in a frame structure and which inthe lower region has mutually oppositely disposed closure members whichare pivotable by a control member and which each include grid barsarranged in parallel spaced relationship with each other, the grid barsbeing mounted in a first rotary mounting which is supported on the framestructure, wherein the grid bars are mounted in the carrier beam memberrotatably about a horizontal axis and elastic supports are associatedwith the grid bars at the points of entry into the container.

By virtue of that configuration of a charging material preheater, it ispossible on the one hand to control the severe shock loadings whencharging material is introduced into the container, insofar as suchloadings are carried by elastic supports and transmitted into the framestructure of the container, while in addition by virtue of theindividual mounting of the grid bars in the carrier beam, it is possibleto replace a damaged grid bar without operation of the charging materialpreheater having to be interrupted for that operation.

SUMMARY OF THE INVENTION

In the case of the charging material preheater of the kind set forth inthe opening part of this specification, the grid bars or fingers of eachclosure member are in the form of cantilevered carriers, which areclamped in position at the end, of a rotatable drum mounted in amounting which is supported on the frame structure of the container.Particularly in the case of high shaft-like containers, that results ina heavy mechanical loading on the rotary mounting and control members iffor example heavy scrap drops on to the fingers from a height of 4meters. Even if the mounting is fixed in the frame structure, with theincorporation of shock absorbers, it is not possible to guarantee thedesired service life, in relation to shock loadings of that kind.

In a charging material preheater of the kind set forth in the openingpart of this specification, the object of the invention is to pass theshock forces which act on the closure members when charging material isintroduced directly into the frame structure without thereby loadingcontrol members. The invention also aims to reduce the loading on therotary mountings of the fingers in the frame structure and thus increasethe durability thereof. The invention further seeks to provide that thea design structure permitting the use of shock absorbers with a greaterspring travel.

In accordance therewith the fingers of a closure member are mountedrotatably in their central portion and an outer portion which is passedoutwardly through an opening in the container wall is mounted by way ofan elbow lever mechanism in a further rotary mounting of the framestructure. In the closed position of the closure members the elbow levermechanism is in the straight position, that is to say the two lever armsof that mechanism are in a straight line, so that control members whichare pivotally connected to the elbow lever mechanism are decoupled fromthe path of the transmission of force by way of the extended elbow levermechanism into the frame structure. In that arrangement associated witheach grid bar is its own elbow lever mechanism. For joint actuation ofthe elbow lever mechanisms, either the lower or the upper lever arms ofthe elbow lever mechanisms of a closure member are connected together bya connecting member, preferably a beam or bar, which is pivotablyengaged by a control member which is supported in a third rotarymounting of the frame structure. Preferably two control members areassociated with the connecting member.

Preferably the fingers in the inclined position of the closure membersare inclined obliquely downwardly, wherein a value of 30° has been foundto be particularly desirable as the angle of inclination relative to thehorizontal, having regard to the shock loading and the aspect of sealingoff the exit openings for the fingers. From that closed position, thefingers are moved through 60° downwardly into the release position inwhich they are substantially aligned with the shaft walls disposedthereabove.

When the fingers are inclined obliquely downwardly, the retardationdistance or travel is increased, in comparison with their horizontalarrangement. With an inclination of 30°, that is about 13%. In addition,the forces which act on the fingers are divided into a componentperpendicular to the finger and a component parallel to the finger. Forthe critical flexural stress immediately in the vicinity of the firstmounting, the component perpendicular to the finger is primarilycrucial. With an angle of inclination of 30° a reduction in the flexuralstress of about 13% is achieved.

Because of the force component which acts parallel to the finger on theimpinging batch of scrap, the direction of the retardation travel ordistance in relation to the center of gravity of the batch of sheetmetal changes and thus also results in an increase in the length of theretardation travel or distance. Having regard to all components, it ispossible in this way to achieve a reduction in the critical load byabout 25%.

For the purposes of damping the shock forces, shock absorbers areprovided either in the lower or in the upper lever arms of the elbowlever mechanisms. In addition, shock absorbers can be provided betweenthe first rotary mountings of the fingers and the frame structure, inthe case of high shock loadings. In that situation, the first rotarymountings are displaceable perpendicularly in guides of the framestructure and are supported on the frame structure by way of shockabsorbers.

It has been found particularly advantageous for the fingers each to bemounted in a respective mounting housing which, together with thefinger, forms a replaceable structural unit. In that way it is possiblefor individual fingers, together with their rotary mountings, to bereplaced during operation of the assembly. In that case the mountinghousings are preferably supported on the frame structure by way ofindividual shock absorbers.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in greater detail by means of embodimentswith reference to 4 Figures of drawings in which:

FIG. 1 is a diagrammatic view of a charging material preheater in whichthe fingers are in the closed position,

FIG. 2 is a view corresponding to FIG. 1 in which the fingers are in therelease position,

FIG. 3 shows a portion of the assembly to illustrate the way in which afinger passes through the container wall, the first mounting beingsupported in this case on the frame structure by way of a shockabsorber, and

FIG. 4 is a perspective view of a part of the assembly showing a firstmounting in the form of a replaceable unit, with a finger, in theinstalled condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The charging material preheater 1 shown in FIG. 2 includes a framestructure in the form of a parallelepipedic cage construction comprisinghorizontal beams or bars 3 and perpendicular pillars 4. Disposed withinthe frame structure 2 is a shaft 5 of approximately rectangularcross-section, the internal space of which is enlarged in a downwarddirection. Disposed in the lower region of the shaft 5 are mutuallyoppositely disposed closure members 7 and 8 which are pivotable by twocontrol members 6 (only the front control member is visible in eachcase). The closure members have respective fingers 9 and 10 which arearranged parallel and at a spacing from each other. FIG. 1 shows afinger 9 of the first closure member 7 and a finger 10 of the secondclosure member 8. The other fingers are respectively disposed parallelthereto from the front wall (not shown) of the shaft to the rear wall 11of the shaft, wherein the spacing between the individual fingers is soselected that, with the closure members 7 and 8 in the position shown inFIG. 1, the fingers 9 and 10 can retain in the shaft charging materialwhich is introduced into the shaft 5 from above, while at the same timean adequate cross-section for heating gases to pass through between theindividual fingers, for preheating the charging material, is guaranteed.

BRIEF DESCRIPTION OF THE DRAWINGS

Fingers 9 and 10 are respectively rotatably mounted in first rotarymountings 12 and 13 respectively. The rotary mounting can be in the formof a journal which is supported on the frame structure (see the mounting12) or in the form of a mounting shell which is supported on the framestructure and which accommodates a rotary shaft on which the finger 10or a group of fingers 10 is fixed (see the mounting 13).

It will be seen from FIG. 1 that the fingers 9 and 10 are mounted by acentral portion in the first mounting 12 and 13 respectively and areeach passed outwardly through an opening 14 and 15 respectively in thecorresponding wall of the shaft, so that, in regard to each finger 9 and10 respectively, there is defined an inner portion which projects intothe internal space of the shaft and an outer portion which, in relationto the inner portion, is on the opposite side of the respective firstrotary mounting.

The outer portion of the respective finger 9 and 10 is mounted in asecond rotary mounting 21 and 22 respectively of the frame structure 2by way of a respective elbow lever mechanism 16 and 17 respectively,each of which comprises a lower arm 18 and an upper arm 19 which areconnected together by a hinge joint 20. In the present case, associatedwith each of the fingers 9 that are arranged in parallel relationship isa respective elbow lever mechanism 16. The same applies in regard to thefingers 10 which are arranged in mutually parallel relationship. It ishowever also possible for two or more fingers of a closure member tohave a common elbow lever mechanism associated therewith. In theillustrated embodiment, for the purposes of joint actuation of allfingers 9 and 10 respectively of a closure member 7 and 8, the upperlever arms 19 of the elbow lever mechanisms 16 and 17 respectively of aclosure member 7 and 8 are connected together by a connecting member,more specifically a respective beam or bar 23 and 24, and that beam orbar is engaged, by way of a Joint 25, by the control member 6 which issupported at a third rotary mounting 26 and 27 respectively on the framestructure. In the present case the control member 6 is a hydrauliccylinder which, in the position shown in FIG. 1, is extended and therebyholds the elbow lever mechanism 16 and 17 in the extended position, thatis to say in a position in which the two lever arms 18 and 19 arealigned with each other. With the elbow lever mechanism in thatposition, the fingers 9 and 10 respectively are in the closed positionshown in FIG. 1. As can also be seen from the Figure, in this embodimentthe second rotary mountings 21 and 22 are higher than the first rotarymountings 12 and 13 respectively and the third rotary mounting 26 and 27are higher than the second rotary mountings 21 and 22 respectively.

In the illustrated embodiment, for the purposes of damping shocks whichact on the fingers 9 and 10 when charging material is introduced intothe shaft 5, due to the energy deriving from the downward fallingmovement thereof, shock absorbers 28 are provided in the lower arms 18of the elbow lever mechanisms 16 and 17 respectively. When chargingmaterial impinges on the fingers, the shock absorbers 28 permit anangular movement of the inner portions of the fingers about themountings 12 and 13 respectively, and in so doing damp the impact shockenergy. The flexural loading on the fingers is substantially reduced inthat way.

As, in the closed position of the closure members 7 and 8, the elbowlever mechanisms 16 and 17 respectively are in their straight orextended position, the shock forces which act on the fingers 9 and 10when charging material is introduced are transmitted by way of thejoints directly to the second mountings 21 and 22 respectively. Thecontrol members 6 are decoupled from the flow of forces.

For the reasons already mentioned, the fingers 9 and 10, in the closedposition of the closure members as shown in FIG. 1, are inclinedobliquely downwardly. An angle of inclination α of about 30° has beenfound to be advantageous. The outer portions of the fingers 9 and 10respectively are angled downwardly. That measure serves to make optimumuse of the available space, with the desired long damping travel ordistance for the shock absorbers 28, and to ensure reliable actuation bythe control members 6.

In the embodiment shown in FIG. 1 the inner portions of the fingers 9are substantially longer than the inner portions of the fingers 10. Thisarrangement provides that, upon pivotal movement of the closure members7 and 8 from the closed position shown in FIG. 1 into the releaseposition shown in FIG. 2, the charging material in the shaft can becharged at one side, more specifically in the present case at one sidetowards the right. This is advantageous if the shaft of the chargingmaterial preheater is used in conjunction with a smelting plant in whichit is mounted laterally in the cover region, because in that way it ispossible for the material to be charged towards the center of thevessel.

FIG. 2 shows the release position of the closure members 7 and 8. Theclosure members are moved from the closed position shown in FIG. 1 intothe release position by the control members 6 being moved from theextended position into the retracted position, whereby the upper leverarms 19 of the elbow lever mechanisms 16 and 17 are raised by way of thebeams or bars 23 and 24 respectively, and thus the fingers 9 and 10 arepivoted about their first mountings 12 and 13 respectively until theirinner portions face approximately vertically downwardly, so that thepassage for material through the shaft is opened. In that situationthe-pivot angle is about 60°.

In a modified embodiment, the portion of structure shown in FIG. 3illustrates the mounting of a finger in a finger housing 29 which issupported on the frame structure 2 by way of a shock absorber 30. Thefirst rotary mounting 12 in which a journal 31 of the finger 9 ismounted is provided in side walls of the finger housing 29. The fingerhousing also has cooling ducts 32 and 33 at the locations which aretowards the opening 14 in the wall of the shaft 5. Conduits 34 and 35are provided for supplying the cooling ducts 32 and 33 with coolingwater. The conduits 34 and 35 are connected to cooling water ducts whichare present in the frame structure 2. The portion of the finger housing29, which faces towards the interior of the shaft and which defines thecooling water duct 32, is provided at the underside with an edge 36which serves to break slag deposits. The Figure shows the releaseposition of the finger 9.

In the event of a shock loading on the finger 9 the finger housing 29 ismoved perpendicularly downwardly and, when that happens, the shockenergy acting on the first mounting 12 is damped by the shock absorber30.

FIG. 4 is a perspective view of a portion of structure corresponding tothat shown in FIG. 3, but in this case the shock absorber 30 isintegrated into the finger housing 29.

Just as in the preceding embodiment, the first rotary mounting 12 isfixedly arranged in the finger housing 29 which is supported on theframe structure 2 by way of the shock absorber, by means of a pull rod36 and connecting elements 37. Disposed on both sides of the fingerhousing 29 are guide walls 38 which are fixedly connected to the framestructure 2 and of which FIG. 4 shows only the rear guide wall. At thesides which are towards the guide walls 38 the finger housing 29 isprovided with slide projections or keys 39 which are guided betweenguide bar portions 40 mounted on the guide walls 38. In that way, in theevent of a shock loading, the finger housing is forced to movevertically, utilising the damping action of the shock absorber.

As can be seen from FIG. 4, the finger housing 29, together with thefinger 9 mounted in the finger housing, is in the form of a replaceablestructural unit which permits replacement of a finger while the chargingmaterial preheater is in operation.

We claim:
 1. A charging material preheater liar preheating chargingmaterial for metallurgical smelting plant, said charging materialpreheater comprisinga shaft fixed in a frame structure and having awall, a lower region and an internal space, and in the lower regionhaving mutually oppositely disposed closure members each of which ispivotable by a control member. said closure members including parallelfingers mounted in a first rotary mounting supported on the framestructure, and said closure members being pivotable downwardly betweenaclosed position in which the inner portion of each of said fingersprojects into the internal space of the shaft to retain chargingmaterial in the shaft and a release position in which the inner portionof each of said fingers faces downwardly and to release the chargingmaterial from the shaft,wherein each of said fingers is mounted by itscentral portion in the first rotary mounting each of said fingers ismounted by its outer portion in a second rotary mounting on the framestructure said outer portion of each finger is passed outwardly throughan opening in the shaft wall by way of an elbow lever mechanism havinglower and upper lever arms which are connected together by a hingejoint, and the lower or the upper lever arms of at least two elbow levermechanisms are connected together by a connecting member which ispivotably engaged by an control member supported in a third rotarymounting of the frame structure.
 2. A charging material preheateraccording to claim 1 wherein in the closed position of the closuremembers the elbow lever mechanisms are in their extended position whenthe closure members are in the closed position.
 3. A charging materialpreheater according to claim 1 wherein of the rotary mountingsassociated with a closure member, the second rotary mounting is arrangedabove the first and the third rotary mounting is arranged above thesecond.
 4. A charging material preheater according to claim 1 whereinthe frame structure is in the form of a parallelepipedic cageconstruction having horizontal beams and vertical pillars.
 5. A chargingmaterial preheater according to claim 1 wherein shock absorbers areprovided in at least one of the lower and the upper lever arms of theelbow lever mechanisms.
 6. A charging material preheater according toclaim 1 wherein the inner portions of the fingers are inclined obliquelydownwardly in the closed position of the closure members.
 7. A chargingmaterial preheater according to claim 1 wherein the angle of rotation ofthe inner portions of the fingers from the closed position into therelease position is in the range of 55° through 65°.
 8. A chargingmaterial preheater according to claim 1 wherein the inner portions ofthe fingers of the one closure member are longer than the oppositelydisposed inner portions of the fingers of the second closure member. 9.A charging material preheater according to claim 1 wherein in the caseof at least some of the fingers, the outer portions are angleddownwardly relative to the inner portions.
 10. A charging materialpreheater according to claim 1 wherein the first rotary mounting issupported on the frame structure by a shock absorber.
 11. A chargingmaterial preheater according to claim 1 wherein each finger is mountedin its own mounting housing which carries the first rotary mounting forthe respective finger and which together with the finger forms areplaceable structural unit.
 12. A charging material preheater accordingto claim 11 wherein the mounting housing is supported on the framestructure by a shock absorber.
 13. A charging material preheateraccording to claim 11 wherein the mounting housing is displaceableperpendicularly between guide walls which are fixed to the framestructure.